Diisopropylethylamine → N-[2-[Cyclopropyl[(2-nitrophenyl)sulfonyl]amino]ethyl]-tetrahydro-3-oxo-1,1-diphenyl-3H-oxazolo[3,4-a]pyrazine-7(1H)-carboxamide

Participants

Reaction Steps

To a solution of N-(2-aminoethyl)-N-cyclopropyl-2-nitrobenzenesulfonamide (0.47 g, 1.7 mmol) and diisopropylethylamine (0.71 mL, 4.1 mmol) in tetrahydrofuran (15 mL) was added 4-nitrophenyl chloroformate (0.33 g, 1.7 mmol) at 0° C., and the mixture was stirred at room temperature for 1 hour. Hexahydro-1,1-diphenyl-3H-oxazolo[3,4-a]pyrazin-3-one (0.40 g, 1.4 mmol) was added thereto, and the mixture was stirred at room temperature for 60 hours. To the reaction solution was added ethyl acetate, and the resulting mixture was washed with 1 N hydrochloric acid, a 1 N aqueous sodium hydroxide solution, water and saturated brine, and dried over magnesium sulfate. The solid was filtered off, and the filtrate was concentrated. The residue was purified with silica gel column chromatography (hexane:ethyl acetate=98:2 to ethyl acetate). The fractions were collected and concentrated. The residue was washed with diethyl ether and collected by filtration to obtain the title compound (0.76 g, yield 92%).

Provenance & Evidence